Hello, I'm a senior support technician and I've often helped user with performance problems on laptops.
The best action would be to make a screen sharing via TeamViewer or another software and allow me to analyse the current status of the laptop.
The possible causes are :
- A hard disk pre-failure condition : when a hard disk has too many bad sectors, it makes a clicking noise and slows down avery action. I can run a disk check to assess if that's the case. (if you own an SSD drive, then it shouldn't slow down)
- Too much memory (RAM) used by background softwares : sometime, even the manufacturer may install many monitoring softwares that you don't specially need, so freeing RAM gives a breath of oxygen to the laptop.
- A high CPU activity (having a core of the processor working at 100% without reason) will often slow down the machine and make the cooling fan work at full speed making an unusual noise.
- if a virus infected the machine, it can also slow it down using too much RAM or CPU
These are the most common, but there are many others.
Sometimes the laptop specs are simply too low for the kind of work you expect from it.
For examples, there are high-end processors like the intel core i7 than are made for engeeniers or gamers as their cache memory is bigger and won't be saturated by many processes working at a time.
On the other hand, you have low-end processor like i3, celeron or atom, that are entirely made for netbooks (you can read your mails, that's all)